Base slab on compacted gravel over a pile cap

[Aakalim103]

I have a situation where we need a floor slab on top of a pile cap. Ideally, the pile cap can serve as a floor slab, but this would give us a very thick pile cap. So instead the manager is proposing a compacted gravel layer on top of the pile slab. The idea is to have a thinner base slab on gravel base in order to reduce the amount of concrete.

My question is that in such a situation, how would i go about designing the floor slab? The gravel will be compacted and laid over a fairly thick and rigid pile cap/mat. Should i use some subgrade reaction for the gravel or should i consider it rigid?

 

[HTURKAK]

As far as I understand,the floor slab supported by partially pile cap but mostly by grade.. You may perform FEM and use softer springs for the span zone and hard springs on the pile cap zone..

A sketch showing the dimensions and section will be helpful to get better responds..